To test how fertilizer affects aquatic animals, a student prepared four identical containers with water fleas. the student then added different amounts of fertilizer mixed with distilled water to three of the containers and distilled water alone to one of the containers. what is the control group in this experiment?

The control group in the given experiment would be the container to which only distilled water is added.  

In the given test done by the student, the amount of fertilizer is the factor, which is being tested in the experiment. In the mentioned experiment, distinct concentrations of fertilizer, which was mixed with distilled water were supplemented to three of the containers.  

The different concentration of the used fertilizer is anticipated to possess a distinct influence and to generate distinct outcomes. This makes the concentration of fertilizer to be the factor, which is being examined in the experiment. The container to which only distilled water is supplemented will function as the control in the experiment.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

the answer would be b i believe